Electron gun structure employing a unitary cylinder housing



Nov. 3, 1970 F. G. OESS 3,533,368

ELECTRON GUN STRUCTURE EMPLOYING A UNITARY CYLINDER HOUSING Filed Jan. 2, 1968 2 Sheets-Sheet 1 w Q Aezazz/cz- 05.55. a 8y Irma/5y haw/ma Nov. 3, 1970 F. G. OESS 3,538,368

ELECTRON GUN STRUCTURE EMPLOYING A UNITARY CYLINDER HOUSING Filed Jan. 2, 1968 2 Sheets-Sheet 2 Patented Nov. 3, 1970 ELEQTRON GUN STRUQTURE EMPLOYING A UNITARY CYLINDER HOUSING Frederick G. Oess, Oceanside, Calif., assignor to Hughes Aircraft Company, Culver City, Calif, a corporation of Delaware Filed Jan. 2, 1968, Ser. No. 695,066 Int. Cl. HOlj 1/88; H073 19/42, 29/00 US. Cl. 313-82 1 Claim ABSTRACT OF THE DISCLOSURE This invention relates to a novel electron gun structure particularly adapted to provide precise physical alignment of the respective components, as well as a light, rugged unit.

characteristically, prior art electron guns have utilized a side rod method to provide physical support for the electron gun components and to maintain same in their relative positions. One such method is known as the glass side rod method of gun construction wherein the respective electrode elements are individually provided with pinlike extensions. During the manufacture of this type of gun the elements are first placed in an appropriate fixture in their correct relative positions. The noted extensions are then physically embedded in two or more heated glass rods which, upon cooling, become physically attached to the extension and thereby support and interconnect the respective electron gun components. An alternate construction is that known as the ceramic side rod method. A brief examination will indicate that guns using this method are similar, generally, to those produced by the glass side method. However, the element extensions utilized in the ceramic side rod method consist of pre-formed metallic straps which are open at one end. Again, the respective components with the protruding strap pairs are placed in appropriate fixtures to maintain their relative position during assembly and the side rod ceramic is inserted into the open strap ends and the latter welded to gether. The ceramic side rods now physically support and interconnect, as well as electrically isolate, the various components of the gun.

Persons experienced in the fabrication of the described prior art electron guns, as well as others well known to the industry, will be aware of the problems created :by such typical structures, for example, that of maintaining alignment accuracy between the respective electron gun components. Improper alignment results in variable and sometimes erratic operation between various guns produced, even those manufactured in a common production.

Additionally, the manufacture of such prior art guns is relatively complex requiring expensive tooling and fixturing, as Well as skillful operator handling.

It is also well known that components of electron guns in their in situs operation will frequently reach temperatures up to 850 C. and this wide temperature band has resulted in operational misalignment or prior art guns due to the fact that materials having different coefficients of expansion and contraction are characteristically used. Other difl'iculties with prior art gun arrangements will occur to those skilled in the art.

With the above in mind it is a primary object of the invention to provide an electron gun structure configured to provide physical integrity and stability and high resistance to shock and vibration.

It is a further object of the invention to provide an electron gun structure having superior physical alignment accuracy, said accuracy being easily obtained during gun manufacture.

It is yet another object of the invention to provide an electron gun having an overall diameter substantially less than prior art configuration which enables it to be encapsulated in a tube neck of smaller diameter, thereby constributing to a reduction in bulk of an assembled de vice, for example, a cathode ray tube.

It is still a further object of the invention to provide an electron gun structure of such configuration that it simplifies the tooling required to fabricate and assemble, as well as reduces the required number of fabrication steps as compared to prior art design, thereby contributing production runs having lower scrap rates.

These and other objects and advantages of the invention will become apparent in the course of the following description and from an examination of the related drawings, wherein:

FIG. 1 is a partially fragmentary isometric view of a triode electron gun incorporating the features of the invention;

FIG. 2 is a vertical sectional view of the triode gun shown in FIG. 1 with some of the structure removed; and

FIG. 3 is a vertical sectional view, similar to FIG. 2, of a tetrode gun structure incorporating features of the invention.

Describing the invention in detail and directing attention to FIGS. -1 and 2, the numeral 10 generally indicates an outer cylinder of elongated metallic construction which, as can be seen, provides support for the entire internal gun structure. At the rear aspect of the gun the cylinder 10 is closed by a ceramic support block 12 having a plurality of support elements 14, 14, as well as eyelets 16, 16 which may accommodate electrical lead passage or carry support straps. The ceramic support block 12 is also centrally apertured as at 18.

An outer G1 support ceramic 20 is pressure mounted to support cylinder 10, as disclosed in my copending application Ser. No. 695,080 entitled Electron Gun Electrode Mounting Arrangement and Method of Fabrication and filed on Jan. 2, 1968. A metallic G1 cup 22 sometimes referred to as a control electrode is carried by the outer ceramic 20 and has positioned therein an inner ceramic 24 which in turn abuts, at its rear end, a cathode support ceramic 26. A cathode centering ring 28 and cathode end or retaining cap 30 are also provided.

The cathode ceramic 26 supports the cathode 32 in proper position along the longitudinal axis of the cylinder 10. A heater assembly 34 is disposed within the cathode 32 and may be provided with an electrical lead 36 to electrically energize same. The G1 cup 22 is provided with a central electron beam passing aperture 38, as well as an electrical lead 40 by which an appropriate electrical potential may be applied to the cup 22, the latter sometimes being denominated the G1 or control electrode. From the above it will be apparent that the G1 electrode, as well as the cathode 32, are electrically isolated within the cylinder 10.

A G2 or accelerating electrode is indicated generally at 42 and comprises a cup 44 having a bottom wall 46 abutting the outer ceramic 20 and an electron beam passing aperture 48 centrally of the bottom wall and aligned with the long axis of the cylinder 10, as well as the aperture 38 of the G1 electrode and the cathode 32. The G2 electrode is secured to the inner surface of the cylinder and accordingly will operate at the potential of the cylinder 10.

At the opposed end of the gun a focus section is indicated generally at 50. The focus section comprises a limiting aperture dish or plate 52 which may be Welded as at 54 to the inner surface of the cylinder 10. The dish 52 is provided with a central aperture 56, the latter accommodating passage of the electron beam and determining its cross-sectional configuration and is accordingly sometimes referred to as the limiting aperture dish or plate.

A metallic focus cylinder 58 is carried concentrically with the long axis of the cylinder 10 by a pair of focus cylinder supporting ceramics 60, 60. Flared insert cylinders 62, 62 are carried by the ceramic 60 and respectively abut the limiting aperture insert plate 52 and the final aperture beam exit dish or plate 64. The final aperture dish or plate 64 is also provided with a central opening or aperture 66, the latter accommodating exit of the electron beam from the gun. An electrical lead '68 may be connected, as for example by welding, to the focus cylinder 58 and may extend externally of the cylinder 10 via opening 70 formed in the wall of the cylinder 10. A more detailed description of a typical focus section construction may be had by reference to my copending patent application Ser. No. 694,944 entitled Focus Lens Structure for an Electron Gun and filed on Jan. 2, 1968. FIG. 2 is a vertical central cross-sectional View of the triode gun shown in FIG. 1 with some of the operating parts removed therefrom.

Referring now to FIG. 3, a vertical transverse crosssectional view of a tetrode gun structure incorporating features of the invention is here disclosed. The numeral 100 indicates generally an outer metallic support cylinder. A G1 or control electrode dish is shown at 102 and includes a control aperture 103 together with inner and outer ceramic support washers 104 and 106, as disclosed in my first referenced patent application.

Forwardly of the ceramic 106 another outer ceramic 108 is provided which may have its outer periphery metallized to accommodate a Weld connection as at 110 to the cylinder 100. An inner ceramic 112 is also provided, the ceramics 112 and 108 cooperating to support a G2 or first accelerating electrode 114 therebetween with its central aperture 116 aligned with the aperture 103 of the G1 electrode 102. A G2 shield 120 is telescopically received within the inner ceramic 12 and isolates the ceramic 112 to prevent charge building thereon. A G3 or second accelerating electrode 122 is connected, as by welding, at 124 to the inner surface of cylinder 100. The G3 electrode is also provided with a central aperture 126 aligned with apertures 116 and 103, respectively.

The focus section of the electron gun shown in FIG. 3 is at the opposed end of cylinder 100 and is indicated generally at 130. The focus section comprises a limiting aperture plate 132 which may be secured to the inner surface of cylinder 100, as by welding, at 134 and is provided with a beam passing aperture 136 aligned with the long axis of cylinder 100 which defines the transverse configuration of the beam in the same mode as the pre- 4 ture 136 and accommodates exit of the electron beam from the gun. It will be seen that the plates 132 and 142 abut the ceramics 138, 138 to provide longitudinal integrity to the entire structure. An electrical lead 148 may be provided spot-welded to cylinder 140 and extending externally of the cylinder via an opening 150.

From the above it will be apparent that the invention embodies a unique single cylinder electron gun and that cylinder provides the function of supporting both the various components of the gun and maintains physical integrity and electrical isolation between the various components. The gun structure disclosed offers increased structural stability and resistance to shock and vibration as compared to prior art design, especially in view of the fact that the components themselves act as reinforcing bulkheads for the outer unitary supporting cylinder. The gun structure is such that it is amenable to simple tooling and ease of fabrication as compared to prior art structures. The design also accommodates superior aperture alignment and resists misalignment during gun operation due to thermal or mechanical shock. Another characteristic is the reduced overall diameter of the gun as compared to prior art designs which admits of simpler encapsulation in an operating device such as the neck of a cathode ray tube, thus tending to reduce the entire bulk of that device. The structure described lends itself to better product uniformity and reduced scrap loss durin g production runs.

The invention as shown is by way of illustration and not limitation and may be modified in many respects, all within the scope of the appended claims.

What is claimed is:

1. An electron gun comprising:

an elongate cylindrical metallic housing having a first end portion and a second end portion;

an electron beam focus structure situated in the neighborhood of said first end portion, said electron beam focus structure including a beam limiting plate having a centrally located aperture; a beam exit plate having centrally located aperture; and metallic beam focusing cylinder interposed between said beam limiting plate and said beam exit plate and insulatively mounted within said housing in concentric relationship with the internal walls of said housing;

a cathode situated at said second end portion; and

an electrode structure situated in the neighborhood of said second end portion and adjacent said cathode, said electrode structure including a control electrode insulatively mounted within said housing adjacent said cathode, a first accelerating electrode insulatively mounted in said housing adjacent said control electrode, and a second accelerating electrode mounted in said housing adjacent said first accelerating electrode on the side thereof opposite from said control electrode, said second accelerating electrode being in electrical contact with said housing.

References Cited FOREIGN PATENTS 12/1956 Great Britain. 9/1957 Great Britain.

US. Cl. X.R. 3l3252, 284

222g?" UNITED STATES PATENT OFFICE CERTIFICATE OF CORRECTION p t N 3,538,368 Dated November 3, 1970 Inventor) Frederick G. Oess It is certified that error appears in the aboveidentified patent and that said Letters Patent are hereby corrected as shown below:

Col. 1, line 43; between "side" and "method" the word --rodshould be inserted.

Col. 1, line 69; "or" should be of--.

Col. 2, line 13, "constributing" should be --contributing.

Col. 3, line 47; "12" should be --112--.

Col. 4 line 40; between "having" and "centrally" the word a-- should be inserted; and also between "and" and "metallic" the word --a-- should be inserted.

Signed and sealed this 29th day of June 1971.

(SEAL) Attest:

EDWARD M.FLETCHER,JR. WILLIAM E. SCHUYLER, JR. Attesting Officer Commissioner of Patents 

